Triangulation sensors, especially laser triangulation sensors, can be used for measuring distances in a contactless manner. However, in this case, usually only the distance of a surface area, onto which a light beam of the triangulation sensor is exactly collimated, can be detected. Differences in height between surface areas, for example, a depth of a tire tread, or transitions such as edges and grooves, cannot thus be directly detected with a triangulation sensor, especially a triangulation sensor with a single light source.
The publication DE 102 12 382 B4 describes a sensor system, in which two separate displacement sensors are used to detect a step height or a thickness of an object.
The publication EP 2348331 A1 describes an optoelectronic sensor for the detection of object edges with at least two light transmitters, which have each a light source and a transmitter optics for the generation of collimated transmitted light beams.